Two IAEA experts examine recovery work on top of Unit 4 of TEPCO’s Fukushima Daiichi Nuclear Power Station two years after the disaster as part of a mission to review Japan’s plans to decommission the facility. (Greg Webb/IAEA)

Seven years after the Fukushima nuclear accident in Japan released radioactive elements into the environment, researchers say those elements pose minimal risk to human or salmon health along British Columbia’s coast.

A team of researchers at Simon Fraser University’s nuclear science lab collected soil and salmon samples from the Quesnel and Harrison rivers and used a high-resolution gamma-ray spectroscopy to search for signs of radioactive isotopes.

The isotopes — Cesium 134 and 137 — are fission fragments that do not exist in nature and, therefore, can be directly attributed to nuclear reactions.

Lead chemist Krzysztof Starosta says that while they found evidence of the isotopes in both soil and salmon, the levels measured were very low. The team believes some of the lingering isotopes date back to 1960s nuclear weapons testing and the 1986 Chernobyl explosion.

“The levels found in both the salmon and soil samples remained below Canada’s safety guidelines, posing minimal risk to B.C.’s salmon and human populations,” Starosta said in a release.

He said it has been a relief to know the effects on the region have been so small, even if that was expected given Western Canada’s distance from Japan.

“Proximity to a nuclear disaster is critical, but wind and weather patterns that carry airborne radioisotopes should also be of concerns. Wherever these radioisotopes land, they will eventually decay and release some degree of radiation,” he said.

The team’s findings were published in the Canadian Journal of Chemistry.

The Fukushima disaster occurred March 11, 2011, when a tsunami knocked out power at the seaside Fukushima Dai-ichi nuclear power plant, causing partial meltdowns in three reactors.

Japan marked the anniversary Sunday with an official ceremony in Tokyo. More than 18,000 people died in the tsunami and 70,000 are still displaced from their homes.